We have a workaround that will group large numbers of sibling folders into "virtual folders" So if we have folders 1...1000, we can set it up to group them into folders [1-100], [101-200], and so on. In order for this implementation to work completely, I need a way to assign a dataitem to the node while it is dynamically populated, so that I can access this object in the NodeExpand handler to add the virtual folder's children. However when I assign the DataItem as the node is added, the property is null in the NodeExpand handler. Since we are already doing dynamic creation and not databinding, is it possible to assign this and have it available later?
FYI: Elsewhere in our code we have this working with the RadComboBox:
RadComboBoxItem c = new RadComboBoxItem("name", "value");
RadComboBox1.Items.Add(c);
RadComboBox1.DataBind();
Thank you.
-Adam
5 Answers, 1 is accepted
The DataItem attribute is accessible only in the NodeDataBound event allowing you to retrieve data from the datasource.
In other words, you would be able to use the DataItem property if you bind the treeview in the NodeExpand event and then hook on the NodeDataBound to access the e.Node.DataItem (from the event arguments) that is being bound to the node.
Hope this helps.
Regards,
Nick
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I've tried a simple example, and I can't seem to get the NodeDataBound event to fire at all. Maybe you can point out what I am missing:
C#
public
partial class _Default : System.Web.UI.Page
{
private int DirectoryID
{
get { return (int)ViewState["DirID"]; }
set { ViewState.Remove("DirID"); ViewState.Add("DirID", value); }
}
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
Initialize(
1);
}
public void Initialize(int aiDirectoryID)
{
DirectoryID = aiDirectoryID;
PopulateTreeView(
new cStorageDirectory(DirectoryID, "RootNode"));
}
private void PopulateTreeView(cStorageDirectory oDir)
{
RadTreeNode rootNode = new RadTreeNode(oDir.Name, oDir.ID.ToString());
rootNode.DataItem = oDir;
rootNode.Expanded =
true;
rootNode.Category =
"Folder";
rootNode.ImageUrl =
"Images/mailfolder.gif";
rootNode.DataBind();
RadTreeView1.Nodes.Add(rootNode);
RadTreeNode childNode = new RadTreeNode("Child", "5");
RadTreeNode childTwo = new RadTreeNode("SubChild", "6");
rootNode.Nodes.Add(childNode);
childNode.Nodes.Add(childTwo);
RadTreeView1.DataBind();
}
protected void RadTreeView1_NodeDataBound(object sender, RadTreeNodeEventArgs e)
{
Console.WriteLine("Node Data Bound");
}
}
ASPX:
<%
@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<%
@ Register Assembly="Telerik.Web.UI" Namespace="Telerik.Web.UI" TagPrefix="telerik" %>
<!
DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<
html xmlns="http://www.w3.org/1999/xhtml" >
<
head runat="server">
<title>Untitled Page</title>
</
head>
<
body>
<form id="form1" runat="server">
<telerik:RadScriptManager ID="RadScriptManager1" runat="server">
</telerik:RadScriptManager>
<div>
<telerik:RadTreeView ID="RadTreeView1" runat="server" OnNodeDataBound="RadTreeView1_NodeDataBound"
OnNodeExpand="RadTreeView1_NodeExpand">
<CollapseAnimation Duration="100" Type="OutQuint" />
<ExpandAnimation Duration="100" />
</telerik:RadTreeView>
</div>
</form>
</
body>
</
html>
Actually, you do not need to assign a datasource to call the DataBind method. However, if you do not set a datasource, the DataItem will be empty in the NodeBound event, as there will not be any data items to bind the TreeNodes to. What exactly do you need to store in the DataItem property?
Regards,
Nick
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The database contains a directory structure. Every time a node is expanded, we are adding the children nodes to the node that was expanded, following your Load-On-Demand examples. However, we may have 10,000 or 100,000 sibling nodes in any given directory. So we are recognizing large numbers of sibling nodes and instead of adding the nodes directly, we are making virtual folders. So if we have folders 1-1000, we may create 10 virtual folders, each containing a subset of the 1000 folders. So the first virtual folder would contain folders 1 through 100, the second 101-200, and so forth. The virtual folders are created programmatically, but they are not stored in the database and beyond creation we have no way of recreating them (we've lost reference to the parent node when it comes time to expand the virtual folder)
Since first posting my question, I have played around quite a bit with a few different methods of this, and I came up with a solution using the custom Attributes object. I store a flag on whether the node is a virtual folder, and if it is, I also store a delimited list of all of the database keys for the children nodes that this folder contains. It seems to work really well. This is ultimately what I was trying to acheive through the use of the DataItem. Assigning an object containing sub-objects to DataItem when the virtual node is first created would be a little bit more classy of a solution, but the delimted attribute string seems to work.
Another thing you could try is to use Custom Attributes to store the needed data on the first Data Bind of the RadTreeView. Later in the NodeExpand event you could access this data and use it to perform the needed operations.
All the best,
Simon
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